Ebola nurse Pauline Cafferkey is back in hospital - the third time since contracting the disease, NHS officials say.

Ms Cafferkey, from South Lanarkshire, first contracted the disease in December 2014 after treating patients in Sierra Leone at the height of the outbreak which killed more than 11,000 people.

She spent almost a month being treated in an isolation unit at London's Royal Free Hospital, and was discharged in January 2015 after it was thought she had recovered from the virus.

But on October 9th last year she was flown from Glasgow back to the Royal Free Hospital by a military plane after an "unusual late complication" caused her to fall ill again, with meningitis caused by Ebola.

Dr Derek Gatherer, from Lancaster University, previously said that people who fight off Ebola produce antibodies that "kill off the virus in most bodily fluids".

But he added: "In areas of the body where the immune system is not particularly active - one of these is the central nervous system...the Ebola virus can survive in very small quantities".

Also at the time of her re-admission last year, Dr Michael Jacobs, from the Royal Free, described the situation as "unprecedented", saying: "This is the original Ebola virus she had many months ago which has been inside the brain, replicating at a very low level, and has now re-emerged to cause this clinical illness of meningitis".

At one point she was described as "critically ill" but she survived and was discharged from hospital again in November last year, with doctors saying the 39-year-old had made a "full recovery".

She was then sent to Glasgow's Queen Elizabeth University Hospital to continue her recovery closer to home and this is also where she is being treated currently.

An NHS Greater Glasgow and Clyde spokesman said: "Under routine monitoring by the Infectious Diseases Unit, Pauline Cafferkey has been admitted to hospital for further investigations".